What Is The "Illusion of Density"?
The "illusion of density" is described as a perceived fullness and visually dense apperance to the hair on the scalp. However, the "illusion of density" is not true density, because a hair transplant can never match an individuals hair loss hair for hair. Additionally, hair restoration does not create new hair it simply transplants existing hair to another location. Most individuals were born with approximately 100,000 hairs on their head prior to experiencing any hair loss. This breaks down to around 100 follicular units per square centimeter (cm2). Unfortunately, there is no hair transplant surgeon that is able to safely transplant 100 follicular units per square centimeter, because the hair grafts may not have enough blood supply to survive . Therefore, the majority of elite hair transplant surgeons transplant around 45-60 follicular units per cm2. It is known that hair loss does not become visible to the human eye until 50% of density has been lost. Therefore, an individual that once had 100 follicular units per cm2 could transplant 50 follicular units per cm2 without a noticeable difference in hair density.
How Is The "Illusion of Density" Different From Native Density?
In most situations, the illusion of density is no different visually than native density however, the difference can become noticeable in certain conditions or circumstances. In order for the "illusion of density" to work the hair must be long enough for the hair follicles to layer or feather over one another to cover the surface area of the scalp. However, if patients cut their hair really short or comb their hair in a way that reduces the layering or feathering effect, the "illusion of density" will be diminished. Native density appears visually dense in all situations with any hair style whether the hair is wet or dry, but the "illusion of density" requires certain hairstyles and the hair to be dry to appear visually full and dense. Therefore, patients must be cognizant of the limitations associated with hair restoration in order to maintain realistic expectations.
The amount of hair grafts required for the "illusion of density" depend on several factors, but also on the individuals own perception. While a hair transplant may appear to be visually dense, it is not truly dense in comparison to how dense the hair was prior to experiencing hair loss. Thus, some patients may find themselves wanting more hair to achieve fullness and density under any circumstance. Unfortunately, the donor supply is a finite resource that may not be abundant enough to cover the entire scalp with ultra-high density as hair loss progresses. Fortunately, most patients have enough donor hair to achieve good density with acceptable coverage, but "acceptable" depends on on the level of hair loss, expectations and patients perception.